Abstract:
Grazing rates and density of the crustacean zooplankton were measured
in Findley and Chester Morse Lakes and Lake Sammamish, Washington.
Sample analysis is incomplete at reporting time, thus estimates of
production from examination of life stage biomass changes was not possible.
Maximum density of crustacean zooplankton was about 10/1 in
the water column of oligotrophic Findley and Chester Morse Lakes and
70/1 in mesotrophic-eutrophic Lake Sammamish during 1972. Densities
averaged about 10 times greater in Lake Sammamish than in the other
lakes. Copepods comprised most of the numbers in all three lakes.
Grazing apparently represents a sizable loss to phytoplankton in the
three lakes feeding rates experimentally determined in situ from
changes in ¹⁴C tagged phytoplankton ranged from nearly one half to
over six times the algal biomass per day. However, feeding rate was
always less than phytoplankton productivity.
